Sized paper



Patented nee-19,1939

UNITED STATES SIZED PAPER Joseph A. Warren, Westbrook, Maine, assignorto S. D. Warren Company, Boston, Mass., a corporation of MassachusettsNo Drawing. Application January '27, 1937, Serial No. 122,664

4 Claims.

This invention relates to paper and its manufacture. Specifically itpertains to paper comprising alkaline pigment filler and surface or tubsizing contributed by non-fatty constituents of soy beans.

In the paper industry the, terms size and ,sizing are used loosely todesignate various classes of materials including'the following:

(1) Those that impart resistance to water, as resin, wax or the like; a(2) Those that impart stifi'ness'or rattle; for example, sodiumsilicate;

(3) Those-that fill pores andharden thesiirface, e. g. starch; 4) Thosethat act as adhesives in binding surface'coatings, as casein, glue, orthe The term fsizi'ng" is also usedto designate a property of paperwhich can be tested by writing on the paper with pen and ink or byfloating the 2 paper upon a bath of ink or other aqueous medium untilthe paper is penetrated thereby. The present invention is concerned withmaterials falling in class (1) above.

It has long been customary to apply to paper,

25 and especially to writing and bond papers, a surface-size or tub-sizecomprising glue, casein, or-

equivalent. protein. Generally such paper is engine-sizedprior to theapplication ofthe surfacesize in order to avoid excessive absorption ofthe 80 expensive proteinsize. It is true, however, that well beaten,unfilled paper, such as bond or writing paper, can be successfullytub-sized even if,

it. has not been previously engine-sized, although such procedurerequires a large quantity of the 85' surface-sizing material. On theother hand, in

the case of book papers, which-ordinarily are less well hydrated andwhich contain a considerable quantity of inert mineral filler such asclay, it has been impossible to size successfully by a surface 40application of protein unless sufilcient of the latter were used so thatthe paper could be said to be coated rather-than sized. That is, thequantity of protein material ordinarily. used in tubsizing', say up to fourpounds per ream, is not 45 sufiicient to give waterfor writing-inkresistance to such unsized clay-filled book paper.

The protein obtained from soy beans is com monly regarded as being anequivalent of casein. In the case of book paperfilled with inertfiller,,

50 soy bean protein and casein are bothinefiective as surface-sizes. If,however, the paper is filled with an alkaline filler such as calciumcarbonate, calcium sulflte, magnesium carbonate, magnesium hydroxide orthe like, it is found that while casein is no more efiective than onclay filled paper, soy protein acts as an effective surfacesize. v

This invention accordingly has for an object 5 the production of surfaceor tubsized paper containingalkaline filler in which the sizing agentis, at least in part, soy protein. Another object is to size papercontaining alkaline filler by applying to the surface thereof a sizecomprising soy flour. A similar object is to make sized alkaline filledpaper by using engine sizing in the furnish and applying to the surfaceasize con taining .soy protein. Other objects and advantages willzbeapparent from the following description:

After the oil has been removed from soy beans by pressure or' preferablyby solvent" extraction, the residual cake contains approximately 45% ofprotein material, the remainder being chiefly carbohydrate material witha small quantity of mineral-matter and some moisture. For use accordingto this invention the protein may be removed from the cake by extractionwith dilute alkali solution, or the cake may be ground to flour whichmay be dispersed in water containing a little alkali, such as ammonia,caustic soda; or the like. *Obviously-the latter procedure is thecheaper and may in many cases be satisfactory. Accordingly, inthisdisclosure the term soy protein is intended to include both therelatively pure-protein and theprotein in association with the otherconstituents going to make up soy flour.

In practicing the invention a paper-making Q furnish comprising fibrousmaterial and alkaline .filling material is formed into a web on a web-'forming device, for example a Fourdrinier wire. .T0 at least one surfaceof theformed web, either before or after partial or complete drying, isapplied an alkaline dispersion of soy-protein or soy 40 fiour and theweb is dried. It'will be found-that the paper so treated has developedresistance to water; that is, it is sized.

The sizing effect is believed to be due to a specific action between thealkaline filler and some 'fite, and calcium carbonate.

sizing efiects are additive, and more sizing is obtained than would begiven by either method alone.

It is possible to mix clay or other pigment in the protein dispersion toform a thin slurry which acts to fill the surface of the paper, andstill get the effect of sizing.

Following is a description of several examples in accordance with theinvention:

The following size compositions were employed:

A. Casein of papercoating grade, 20 parts, cooked with watercontaining 7parts ofstrong ammonia water, to make a 5% casein solution.

B. Soy protein waspreparedfrom solvent-ex-' tracted soy meal byextraction with-dilute caustic soda solution. The protein wasprecipitated from solution by acid, and dried.

20 parts of the dried protein were dissolved by '7 parts'of strongammonia water in 373 parts of water to make a 5% soy protein solution.

C. Lime-soluble soy protein was prepared from soy meal by extractionwith calcium hydroxide solution. The protein was precipitated fromsolution by acid, and dried.

20 parts of the dry lime-soluble protein was dissolved by '7' parts ofstrong ammonia water in 3'73 parts of water to make a 5% solution.

D. Soy flour was prepared by grinding solventextracted soy meal in aball mill, and passing it through bolting cloth.

30 parts of the dry flour were dispersed in 570 parts of watercontaining 0.5 part of sodium hydroxide;

E. 30 parts of soy flour were dispersed in 560 parts of water and partsof strong ammonia water.

F. parts of soy flour and 15 parts of china clay were dispersed in 565parts of water and 5 applied the various protein dispersions listedabove. As mineral filling materials for, the paper were used the inertmaterial clay; and the alkaline materials magnesium carbonate, calciumsul- In some cases the protein dispersgi was applied at a size-pressafter theweb had been pressed but not dried; in other cases the proteindispersion was applied to the surface of the dried paper.

The samples prepared as described were tested by being written uponwithpen and ink or by being floated on an ink bath. The former test showedmerely whether or not the paper was sized, while the latter test gave anindication of the degree of sizing obtained. The results of the sizingtests are shown in the following two tables which .likewise indicate themineral filling ma- -erial in the sheet, the dry weight of the proteinsize dispersion applied to the sheet, and whether the size was appliedbefore or after the sheet was dried. Table 1 shows the effect of caseinand soy protein, each on clay-filled and on alkaline-filled paper. Table2 shows the effect of various soy sizes on each of several paperscontaining difierent alkaline fillers,

Table 1 W i b l ded P eg tsze oreoi' en and F111 m added after ink testdrying A, 1.5 lbs. Not sized. B, 1.1 lbs. Do. G, 0.9 lbs.. Do. A, 3.5lbs Do. B, 3.2 lbs.. Do. A, 1.6 lbs.. I) B, 1.4 lbs. G, 0.9 lbs. A, 3.5lbs. B, 3.2 lbs.

Table 2 V w ht bAfdded Secondsk eig size e ore or sizing, in ruler paperadded after flotation drying test I Calcium carbonate, 30% Size F, 2.4lbs. 8 secs. Do Size E, 1.0 lb 3 5808. Do Size E, 3.5 lbs. 13 secs.Calcium carbonate, 18% Size D, 2.7 lbs.. 7 secs. Do Size 0, 3.7 lbs.. 9secs. Calcium sulfite, 22%. Size E, 2.6 lbs.. 7 secs. Mfs giesiumcarbonate, Size E, 2.8 lbs.. 10 secs.

The percentages of mineral filler shown in the foregoing tables arebased on the air-dry weight of the finished sheet of paper beforeapplication of the surface size. dry weights thereof applied to a60-pound ream (25 x 38 inch-500sheets) of base paper.

In another example a 60-pound paper was prepared containing soda andsulfite fiber and 20% of calcium carbonate, the furnish having beenengine-sized with premixed rosin size and alum. This paper had atwo-second ink flotation test, but would not stand pen and ink writing.To this dry sheet was then applied two pounds dry weight of sizedispersion E. After drying the. ink flotation test was now 8 seconds,and the paper could be written upon with pen and ink. 1

Whether the action of soy protein with alkaline filler as hereindisclosed is chemical or physical in nature,.it is evidently differentthan and distinct from its action with inert filler. For the practice ofthis invention imparts to paper containing alkaline filler a degreeofmoisture resistance not given by the same treatment to paper containingonly'inert filler. Neither is the moisture resistance given to alkalinefilled paper by the soy protein-alkaline filler action duplicated by theaction of casein or glue on the same paper. But when soy protein or soyflour is applied by well-known surface-sizing methods to alkaline filledpaper, and especially to book paper containing alkaline filler, thepaper so treated is rendered reliably moisture-resistant and may be saidto be satisfactorily sized.

I claim:

1. An alkaline filled, uncoated paper, surface sized with a soya beanprotein size, said size consisting essentially of soya bean protein.

2. An alkaline filled, surface sized, uncoated paper as defined in claim1 in which the soya bean protein size consists of isolated soya beanprotein.

.3. An alkaline filled, surface sized, uncoated paper as defined inclaim 1 in which the soya bean protein size consists of soya bean flour.

4. An alkaline filled, surface sized, uncoated paper as defined in claim1 containing rosin engine sizing.

JOSEPH A. WARREN.

The weights of size are the-

